Add CASSANDRA_CGROUP_MEMORY_LIMIT env var

Author: vroyer

README.md

@@ -90,6 +90,18 @@ LOGBACK_org_elassandra_cluster_service
 LOGBACK_org_elasticsearch
 ```
 
+### cgroup memory limit
+
+If CASSANDRA_CGROUP_MEMORY_LIMIT is set to **true** (default is **false**), 
+add the following JVM properties to the /etc/cassandra/jvm.options file.
+This will restrict maximum heap size to cgroup limit.
+
+```
+-XX:+UnlockExperimentalVMOptions
+-XX:+UseCGroupMemoryLimitForHeap 
+-XX:MaxRAMFraction=2
+```
+
 ### Kubernetes
 
 A **ready_probe.sh** script can be used for readiness probe as follow:

docker-entrypoint.sh

@@ -159,7 +159,13 @@ if [ "$1" = 'cassandra' ]; then
   if [ "$LOCAL_JMX" = "no" ]; then
   	 export JVM_OPTS="$JVM_OPTS -Djava.rmi.server.hostname=$POD_IP"
   fi
-    
+  
+  : ${CASSANDRA_CGROUP_MEMORY_LIMIT='false'}
+
+  # Specifies if heap size should be limited by cgroup constraints
+  if [ "${CASSANDRA_CGROUP_MEMORY_LIMIT}" = 'true' ]; then
+     export JVM_OPTS="$JVM_OPTS -XX:+UnlockExperimentalVMOptions -XX:+UseCGroupMemoryLimitForHeap -XX:MaxRAMFraction=2"
+  fi  
 fi
 
 exec "$@"